org.mapdb

Class StoreHeap

java.lang.Object

org.mapdb.Store

org.mapdb.StoreHeap

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable, Engine

public class StoreHeap
extends Store

Store which keeps all instances on heap. It does not use serialization.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	StoreHeap.Snapshot

Nested classes/interfaces inherited from class org.mapdb.Store

Store.Cache, Store.LongLongMap, Store.LongObjectMap<V>, Store.LongObjectObjectMap<V1,V2>, Store.LongQueue, Store.MemoryBarrierLessLock, Store.ReadWriteSingleLock

Nested classes/interfaces inherited from interface org.mapdb.Engine

Engine.CloseOnJVMShutdown, Engine.ReadOnly, Engine.ReadOnlyWrapper

Field Summary

Fields inherited from class org.mapdb.Store

LOCKING_STRATEGY_NOLOCK, LOCKING_STRATEGY_READWRITELOCK, LOCKING_STRATEGY_WRITELOCK, NOLOCK

Fields inherited from interface org.mapdb.Engine

CLOSED_ENGINE, RECID_CLASS_CATALOG, RECID_FIRST, RECID_LAST_RESERVED, RECID_NAME_CATALOG, RECID_RECORD_CHECK

Constructor Summary

Constructors

Constructor and Description
StoreHeap(boolean txDisabled, int lockScale, int lockingStrategy, boolean snapshotEnable)

Method Summary

Modifier and Type	Method and Description
void	backup(java.io.OutputStream out, boolean incremental)
void	backupRestore(java.io.InputStream[] in)
boolean	canRollback()
void	close() Close store/cache.
void	commit() Makes all changes made since the previous commit/rollback permanent.
void	compact()
<A> boolean	compareAndSwap(long recid, A expectedOldValue, A newValue, Serializer<A> serializer) Updates existing record in atomic (Compare And Swap) manner.
boolean	fileLoad() If underlying storage is memory-mapped-file, this method will try to load and precache all file data into disk cache.
long	getCurrSize()
long	getFreeSize()
long	preallocate() Preallocates recid for not yet created record.
<A> long	put(A value, Serializer<A> serializer) Insert new record.
void	rollback() Undoes all changes made in the current transaction.
Engine	snapshot() Returns read-only snapshot of data in Engine.
<A> void	update(long recid, A value, Serializer<A> serializer) Update existing record with new value.

Methods inherited from class org.mapdb.Store

canSnapshot, clearCache, delete, forDB, forEngine, get, getWrappedEngine, init, isClosed, isReadOnly, metricsCollect

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

StoreHeap

public StoreHeap(boolean txDisabled,
                 int lockScale,
                 int lockingStrategy,
                 boolean snapshotEnable)

Method Detail

update

public <A> void update(long recid,
                       A value,
                       Serializer<A> serializer)

Description copied from interface: Engine

Update existing record with new value.

Recid must be a number returned by 'put' method. Behaviour for invalid recid (random number or already deleted record) is not defined, typically it throws 'EndOfFileException', but it may also corrupt store.

Specified by:

update in interface Engine

Overrides:

update in class Store

Parameters:

recid - (record identifier) under which record was persisted.

value - new record value to be stored

serializer - used to serialize record into binary form

compareAndSwap

public <A> boolean compareAndSwap(long recid,
                                  A expectedOldValue,
                                  A newValue,
                                  Serializer<A> serializer)

Description copied from interface: Engine

Updates existing record in atomic (Compare And Swap) manner. Value is modified only if old value matches expected value. There are three ways to match values, MapDB may use any of them:

1. Equality check oldValue==expectedOldValue when old value is found in instance cache
2. Deserializing oldValue using serializer and checking oldValue.equals(expectedOldValue)
3. Serializing expectedOldValue using serializer and comparing binary array with already serialized oldValue

Recid must be a number returned by 'put' method. Behaviour for invalid recid (random number or already deleted record) is not defined, typically it throws 'EndOfFileException', but it may also corrupt store.

Specified by:

compareAndSwap in interface Engine

Overrides:

compareAndSwap in class Store

Parameters:

recid - (record identifier) under which record was persisted.

expectedOldValue - old value to be compared with existing record

newValue - to be written if values are matching

serializer - used to serialize record into binary form

Returns:

true if values matched and newValue was written

getCurrSize

public long getCurrSize()

Specified by:

getCurrSize in class Store

getFreeSize

public long getFreeSize()

Specified by:

getFreeSize in class Store

fileLoad

public boolean fileLoad()

Description copied from class: Store

If underlying storage is memory-mapped-file, this method will try to load and precache all file data into disk cache. Most likely it will call MappedByteBuffer.load(), but could also read content of entire file etc This method will not pin data into memory, they might be removed at any time.

Specified by:

fileLoad in class Store

Returns:

true if this method did something, false if underlying storage does not support loading, or is already in-memory

backup

public void backup(java.io.OutputStream out,
                   boolean incremental)

Specified by:

backup in class Store

backupRestore

public void backupRestore(java.io.InputStream[] in)

Specified by:

backupRestore in class Store

preallocate

public long preallocate()

Description copied from interface: Engine

Preallocates recid for not yet created record. It does not insert any data into it.

Returns:

new recid

put

public <A> long put(A value,
                    Serializer<A> serializer)

Description copied from interface: Engine

Insert new record.

Parameters:

value - records to be added

serializer - used to convert record into/from binary form

Returns:

recid (record identifier) under which record is stored.

close

public void close()

Description copied from interface: Engine

Close store/cache. This method must be called before JVM exits to flush all caches and prevent store corruption. Also it releases resources used by MapDB (disk, memory..).

Engine can no longer be used after this method was called. If Engine is used after closing, it may throw any exception including NullPointerException

There is an configuration option DBMaker.Maker.closeOnJvmShutdown() which uses shutdown hook to automatically close Engine when JVM shutdowns.

commit

public void commit()

Description copied from interface: Engine

Makes all changes made since the previous commit/rollback permanent. In transactional mode (on by default) it means creating journal file and replaying it to storage. In other modes it may flush disk caches or do nothing at all (check your config options)

rollback

public void rollback()
              throws java.lang.UnsupportedOperationException

Description copied from interface: Engine

Undoes all changes made in the current transaction. If transactions are disabled it throws UnsupportedOperationException.

Throws:

java.lang.UnsupportedOperationException - if transactions are disabled

canRollback

public boolean canRollback()

Returns:

true if engine supports rollback

snapshot

public Engine snapshot()
                throws java.lang.UnsupportedOperationException

Description copied from interface: Engine

Returns read-only snapshot of data in Engine.

Throws:

java.lang.UnsupportedOperationException - if snapshots are not supported/enabled

compact

public void compact()